Overbed table

ABSTRACT

Disclosed is an overbed table, having a one-way lock mechanism including a cam member which moves a cylindrical element into a locking position during downward movement of the table top, and which permits movement of the cylinder out of the locking position upon upward movement of the table top.

Elite States Patent 1 1 3,715,997

Earth Feb. 13, 1973 1 OVERBED TABLE 1,101,552 6/1914 Hume ..248/412 1vddd Edward Bad-dd Bdwmdddddd 1522??? 13/133ilia'iiiiiji3:13:1:11:11ijiiijiiiiiiiiS/Tii 3,380,405 4/1968 Barecki..108/146 X Assigneez Sybron Corporation Rochester, 3,481,286 12/1969 LaMar ..108/144 Primary ExaminerFrancis K. Zugel [22] Filed: Oct. 12, 1971Attorney-Theodore B. Roessel [21] Appl. No.: 188,390 [57] ABSTRACTDisclosed is an overbed table, having a one-way lock [52] US. Cl...108/146, 108/146, 248/412 mechanism including a cam member which movesa [51] hit. C1. ..A47b 9/08 cylindrical element into a locking positionduring [58] Field of Search .108/148, 144, 146', 248/412, downwardmovement of the table top, and which Pep 248/41 1 mits movement of thecylinder out of the locking position upon upward movement of the tabletop. [56] References Cited 9 Claims, 3 Drawing Figures UNITED STATESPATENTS 909,223 1/1909 Reynolds ..108/148 X PAIENIEUFEUI3 I975 3,715,997

SHEET 10F 2 ATTORNEY PATENTED FEB 1 3 I975 SHEET 2 BF 2 FIG. 3

INVENTOR.

DAVID E. BARTH ATTORNEY OVERBEDTABLE BACKGROUND OF THE INVENTION Thepresent invention relates to overbed tables, as are commonly used inconjunction with hospital beds, and more particularly, to a one-way lockfor such tables which moves into a locking position during downwardmovement of the table top and which moves into an unlocking positionupon upward movement of the table top. Such tables are describedgenerally, for example, in US. Pat. No. 3,314,384.

Overbed tables, sometimes referred'to in the art as cantilever tables,generally comprise a base of substantial length mounted upon castors anda table top generally overlying the base. A column extends verticallybetween the base and the table top so that the table may be rolled up tothe side of the bed with the base extending beneath the bed and thetable top extending over the bed.

It is desirable that tables of this type be vertically adjustable tosuit the convenience of the user and other variable factors whereinheight adjustment is accomplished by telescoping the column on which thetable top is mounted. Thus the present invention is primarily concernedwith the construction of the adjustable column on which the table top ismounted, and more particularly, to the means for smoothly adjusting thetable top and for safely retaining the table top at the desired adjustedheight. In this latter respect, it is preferred that the means forlocking the table top at various positions be of a type whichautomatically releases when the table is moved upwardly. This is toensure that if, through inadvertence, the bed is raised while the tabletop is in an interfering position over the bed, a patient lying on thebed will not be injured nor the table damaged. It is also desirable thatthe means for locking the table top in various positions will allow aninfinite adjustment throughout the entire range of vertical movement.

SUMMARY OF THE INVENTION The present invention may be characterized inone aspect thereof by the provision of an overbed table, having a fixedpost upstanding from a base; a hollow column depending on the table topand telescoping over the post; lock means operable between the columnand the post including a cylindrical member and a cam surface on theinterior wall of the hollow column, the cylinder binding between thepost and cam surface to lock the column against downward movement, andmoving out of the binding engagement when an upward force is applied tothe column to free the column for upward movement; and manual releasemeans for moving the cylinder to an unbinding position to permitdownward adjustment of the table top.

OBJECTS OF THE INVENTION One object of the present invention is toprovide a lock means for overbed tables which permits an infinite heightadjustment of the table top over the entire range of travel.

Another object of the present invention is to provide a lock means foroverbed tables which automatically unlocks when an upward force isapplied to the table top without the use of release levers, handles orthe like.

A further object of the present invention is to provide a lock of thetype described having a minimum of parts and which is efficient inoperation and inexpensive to manufacture.

These and other objects, advantages and characterizing features of thepresent invention will become more apparent upon consideration of thefollowing detailed description thereof, when taken in connection withthe accompanying drawings depicting the same.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a typicaloverbed table in a partly raised position;

FIG. 2 is a foreshortened side elevation view of the support column,partly broken away and in section, showing the internal lock mechanism;and

FIG. 3 is a rear view of the support column as shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, FIG.1 shows a typical overbed table, generally indicated at 10. The tableincludes a wheeled base 12, a table top 14, generally overlying thebase, and a vertical column 16 extending between the base and the tabletop adjacent a corresponding edge of each. The column is made of twoportions, a post 18 which is fixed to and upstands from base 12 and ahollow column member 20, which depends from the table top and telescopesover post 18. The table also includes a lock mechanism (to be describedhereinbelow), for lockingjthe telescoping column at any adjusted heightand a latch member 22, adjacent the top of the table for unlocking thelock mechanism.

Referring to FIGS. 2 and 3, the axial relationship between post 18 andcolumn member 20 is maintained by guides and rollers 26, attachedadjacent the top of post 18 and by guides 28 carried adjacent the lowerportion of column member 20.

Any suitable counterbalancing means can be used to assist in the liftingof the table top. For example, FIG. 3 shows a typical counterbalancingsystem in overbed tables, which consists of a coiled leaf spring 30which has one end attached adjacent the lower portion of column member20 as indicated by the reference numeral 32. The other end of spring 30is coiled about a roller member 34, journaled adjacent the top of post18.

The telescoping travel of column member 20 is limited at its shortestheightby the engagement of rollers 26 against the underside of the tabletop and the greatest height is limited by the engagement of a stop 36 onthe post against the top of a locking block 38 carried adjacent thelower portion of the column member.

Means for locking column 16 at any adjusted height is generallyindicated at 40 (FIG. 2). This means includes a pair of spaced lockingblocks 38 which are fixed to the interior wall 45 of column member 20adjacent its lower portion by any suitable means such as screws 42. Eachlocking block has a vertically oriented cam surface 44 which tapersupwardly, so that the lower portion of the cam surface is closer to theinterior wall 45 of the column member than the upper portion of the camsurface. Extending down between the post and column member adjacentinterior wall 45, is a release rod 46.

As best seen in FIG. 2, the lower end 48 of the release rod is bentinward toward the post, in an L- shape. Just above end 48 are flanges 50which together with the bent end define a space 52 therebetween. Locatedin space 52 and normally resting on the bent end 48 is a horizontallyoriented locking rod or cylinder 54.

Release rod 46, as shown in FIG. 3, extends down between the two lockingblocks 38 and supports the locking cylinder 54 adjacent the centralportion of the cylinder, wherein the ends 56 of the cylinder extendoutwardly from each side of the release rod for engagement with the camsurfaces 44.

The upper end 60 (FIG. 2) of the release rod 46 is carried by latch 22pivoted adjacent the table top. Any suitable means, such as a spring 58,biases latch 22 and therefore maintains a thrust on rod 46 in an upwarddirection. Thus, the latch is lifted for moving the release rod 46downwardly against bias of spring 58.

The operation of the lock means of the present invention is bestillustrated in FIG. 2. As shown in FIG. 2, the lock is obtained by thelocking cylinder 54 becoming wedged between cam surface 44 and the innerpost 18. As more weight is placed on the table top, downward movement ofthe outer column tends to rotate the cylinder clockwise up the camsurface so that downward movement is resisted by the locking cylinderbecoming more tightly wedged between cam surface 44 and the post 18.However, when upward pressure is applied to the table top, the upwardmovement of column member 20 tends to rotate the cylindercounterclockwise as viewed in FIG. 2 to carry the locking cylinderawayfrom cam surface 44. This unwedges the cylinder so that there is noresistance to upward movement of the table top. When downward adjustmentof the table top is necessary, latch 22 is operated to drive the releaserod 46 downwardly. This causes flanges 50 to engage the locking cylinder54 and drive it down and out of its wedged position between cam surface44 and post 18 to the unwedge position. With the locking cylinderreleased from between cam surface 44 and post 18, the table top may bemoved downwardly to any desired position. Releasing latch 22 causes thespring bias to move release rod 46 and locking cylinder 54 upwardly torestore the locking engagement.

Having thus described the invention in detail, it should be appreciatedthat the present invention accomplishes its intended objects inprovidinga one-way lock mechanism for an overbed table which has aminimum of moving parts and which effectively locks the table in adownward direction. The cam and locking roller arrangement allows thetable to free lift", that is, to move in an upward direction whenever anupward pressure is applied to the table, without a necessity of havingto unlock the locking mechanism.

Having thus described the invention, what is claimed as new is:

1. In an overbed table having a horizontally extending base and a tabletop generally overlying said base, column means extending verticallybetween the base and the table top adjacent a corresponding edge of eachincluding a post fixed to and extending upwardly from the base and ahollow column member depending from the table top and telescoping overthe post, an improved one-way lock means to resist downward movement andpermit free upward movement of the hollow column member with respect tothe post, said lock means comprising:

a. a cylindrical lock member disposed between said post and columnmember adjacent the lower end of said column member, the axis of saidcylinder being substantially horizontal;

b. a cam fixed to the interior wall of said column member, said camhaving its cam surface facing toward said post and aligned normal to theaxis of said cylinder;

. a rod extending down between said post and hol low column member, saidrod having its lower end bent beneath said cylinder for supporting saidcylinder between said cam surface and post;

d. said cylinder being engaged and rotated by said cam surface intobinding engagement between said cam surface and said post when downwardpressure is applied to said column member to prevent downward movementof said column member and said cylinder being rotated by said camsurface out of binding engagement between said cam surface and post whenupward pressure is applied to said column member to free said columnmember for upward movement; and

means operable for moving said cylinder downwardly out of bindingengagement between said cam surface and post to permit downward movementof said column member.

2. An overbed table as set forth in claim I, wherein said rod isvertically movable and is biased upwardly to maintain said cylinderagainst said cam surface.

3. An overbed table as set forth in claim 2, wherein said meanscomprises:

a. a flange on said rod spaced above said lower end;

and

b. manually operable means, located adjacent said table top, for movingsaid rod downwardly against said bias to engage said flange against saidcylinder and move said cylinder out of engagement with said cam surface.

4. An overbed table as set forth in claim 3, wherein the lower portionof said rod is bent beneath the central portion of said cylinder withthe ends of said cylinder extending outwardly from said rod.

5. An overbed table as set forth in claim 4, wherein a pair of cammembers is provided, one on each side of said rod.

6. In an overbed table having a horizontally extending base and a tabletop generally overlying and connected to the base by a telescopingcolumn connected to an adjacent edge of each, wherein the columnincludes a fixed post upstanding from base and a hollow column dependingfrom the table top and telescoping over the post, an improvement one-waylock for locking the table top against downward movement whichautomatically unlocks when the table top moves upward, said one-way lockcomprising:

a. a vertically movable rod extending down between said post and hollowcolumn, the lower end of said rod being bent inward toward said post;

b. a flange on said rod above said lower end;

0. a horizontally oriented cylinder resting on the bent end of said rodand in the space between said bent end and flange, the ends of saidcylinder extending outwardly from each side of said rod;

d. a vertically oriented cam surface on the interior wall of said hollowcolumn adjacent said cylinder, the upper portion of said cam surfaceextending from the interior wall of said hollow cylinder a greaterdistance than the lower portion;

I said cylinder being moved up off of said bent end means moving saidrod downwardly when said cylinder is in a locked position for engagingsaid flange against said cylinder and driving said cylinder from thelocked position to unlock said hollow column and permit downwardmovement of said column.

7. An overbed table as set forth in claim 6, wherein said rod isnormally biased upwardly and said means moves said rod downwardlyagainst said bias.

8. An overbed table as set forth in claim 7, wherein the upper portionof said rod is adjacent said table top and is provided with manuallyoperable means for moving said rod downwardly against said bias.

9. An overbed table as set forth in claim 6, wherein a pair of camsurfaces is provided, one adapted to engage each outwardly extending endof said cylinder.

1. In an overbed table having a horizontally extending base and a tabletop generally overlying said base, column means extending verticallybetween the base and the table top adjacent a corresponding edge of eachincluding a post fixed to and extending upwardly from the base and ahollow column member depending from the table top and telescoping overthe post, an improved one-way lock means to resist downward movement andpermit free upward movement of the hollow column member with respect tothe post, said lock means comprising: a. a cylindrical lock memberdisposed between said post and column member adjacent the lower end ofsaid column member, the axis of said cylinder being substantiallyhorizontal; b. a cam fixed to the interior wall of said column member,said cam having its cam surface facing toward said post and alignednormal to the axis of said cylinder; c. a rod extending down betweensaid post and hollow column member, said rod having its lower end bentbeneath said cylinder for supporting said cylinder between said camsurface and post; d. said cylinder being engaged and rotated by said camsurface into binding engagement between said cam surface and said postwhen downward pressure is applied to said column member to preventdownward movement of said column member and said cylinder being rotatedby said cam surface out of binding engagement between said cam surfaceand post when upward pressure is applied to said column member to freesaid column member for upward movement; and e. means operable for movingsaid cylinder downwardly out of binding engagement between said camsurface and post to permit downward movement of said column member. 1.In an overbed table having a horizontally extending base and a table topgenerally overlying said base, column means extending vertically betweenthe base and the table top adjacent a corresponding edge of eachincluding a post fixed to and extending upwardly from the base and ahollow column member depending from the table top and telescoping overthe post, an improved one-way lock means to resist downward movement andpermit free upward movement of the hollow column member with respect tothe post, said lock means comprising: a. a cylindrical lock memberdisposed between said post and column member adjacent the lower end ofsaid column member, the axis of said cylinder being substantiallyhorizontal; b. a cam fixed to the interior wall of said column member,said cam having its cam surface facing toward said post and alignednormal to the axis of said cylinder; c. a rod extending down betweensaid post and hollow column member, said rod having its lower end bentbeneath said cylinder for supporting said cylinder between said camsurface and post; d. said cylinder being engaged and rotated by said camsurface into binding engagement between said cam surface and said postwhen downward pressure is applied to said column member to preventdownward movement of said column member and said cylinder being rotatedby said cam surface out of binding engagement between said cam surfaceand post when upward pressure is applied to said column member to freesaid column member for upward movement; and e. means operable for movingsaid cylinder downwardly out of binding engagement between said camsurface and post to permit downward movement of said column member. 2.An overbed table as set forth in claim 1, wherein said rod is verticallymovable and is biased upwardly to maintain said cylinder against saidcam surface.
 3. An overbed table as set forth in claim 2, wherein saidmeans comprises: a. a flange on said rod spaced above said lower end;and b. manually operable means, located adjacent said table top, formoving said rod downwardly against said bias to engage said flangeagainst said cylinder and move said cylinder out of engagement with saidcam surface.
 4. An overbed table as set forth in claim 3, wherein thelower portion of said rod is bent beneath the central portion of saidcylinder with the ends of said cylinder extending outwardly from saidrod.
 5. An overbed table as set forth in claim 4, wherein a pair of cammembers is provided, one on each side of said rod.
 6. In an overbedtable having a horizontally extending base and a table top generallyoverlying and connected to the base by a telescoping column connected toan adjacent edge of each, wherein the column includes a fixed postupstanding from base and a hollow column depending from the table topand telescoping over the post, an improvement one-way lock for lockingthe table top against downward movement which automatically unlocks whenthe table top moves upward, said one-way lock comprising: a. avertically movable rod extending down between said post and hollowcolumn, the lower end of said rod being bent inward toward said post; b.a flange on said rod above said lower end; c. a horizontally orientedcylinder resting on the bent end of said rod and in the space betweensaid bent end and flange, the ends of said cylinder extending outwardlyfrom each side of said rod; d. a vertically oriented cam surface on theinterior wall of said hollow column adjacent said cylinder, the upperportion of said cam surface extending from the interior wall of saidhollow cylinder a greater distance than the lower portion; e. saidcylinder being moved up off of said bent end and against said post bysaid cam surface to bind said cylinder therebetween when downwardpressure is applied to said column to lock the same against verticaldownward movement, and said cylinder dropping onto said bent end whenupward pressure is applied to said hollow column to unlock the same; andf. means moving said rod downwardly when said cylinder is in a lockedposition for engaging said flange against said cylinder and driving saidcylinder from the locked position to unlock said hollow column andpermit downward movement of said column.
 7. An overbed table as setforth in claim 6, wherein said rod is normally biased upwardly and saidmeans moves said rod downwardly against said bias.
 8. An overbed tableas set forth in claim 7, wherein the upper portion of said rod isadjacent said table top and is provided with manually operable means formoving said rod downwardly against said bias.